Thank you for taking the time to explain, we do indeed seem to be closer to each other's understanding.

So the frequency of a repeated waveform and the shape of the waveform are not interchangeable. Hence my conclusion is that despite... theoretically the amount of energy may be the same, there is a difference in how the energy is transferred.

This is contrary to what I remember having been taught about biomechanics and hearing, but as memory and understanding is unreliable, I'll cede that I'd need to look up a reference for better precision.

The crux of my argument hinges on there not being a difference. And my understanding of the physiology is that the hairs will primarily bend with pressure, and exhaust with flexion (repeated bending cycles leads to breaking), within the limits of survivable amplitudes.

If there isn't a difference, my argument continues in that it's physically very difficult to create a pulse with a ramp up faster than the 20 kHz the ear is evolved to take, that's 0,05 ms, not many physical processes go that fast to create a pressure wave and those that do typically get dispersed very quickly, unless as part of a harmonic excitation.

But of course all that is irrelevant if that's not how the ear reacts.

headphones. Those limits are with respects of quality of sound reproduction.

You may be right, the details of what the measure represents haven't been presented.

From context where it's being argued as a legal argument, I have assumed it to be part of the safety design, and not of sound reproduction.

Ear phones/plugs have no business reproducing good quality sound at >100 dBA, and would be sued into oblivion as the hearing damage and tinnitus reports rolled in. Which to be fair, is what the OP is about.

Having a physical limit at 105 dB would then be congruent with the same unused overhead you refer to, as it corresponds to a doubling of potential sound pressure, and is about typical as overcapacity for high fidelity engineering applications.

faulty earbuds that emitted bursts of painful high frequency noise despite playback being of moderate volume.

105 dB would probably be painful, and as a surprise would be jarring, which contributes to the perceived risk of injury. It should also not be loud enough to cause lasting physical injury, and you'd typically have full functionality within two weeks.

An earbud/head phone can be designed failsafe, so that casing, driver, or most commonly membranes will break at too high amplitudes. If nothing else, it will be limited by the amount of energy available, which for wireless or portable headphones is typically very low. I can't vouch for the specific gear in the OP, but given the rarity of recalled gear due to injury, I'd guess it would be widespread industry practice to design it fail safe.

What I'm saying is that it can still be hardware/physically limited at 105 dB, even though it gave a painful squelch before breaking.

I apologize for my frustration. I've been experiencing lately that I try to communicate one thing and the recepient keep projecting it into their own frame of reference and insist I'm talking of something that I'm not. I'm a bit touchy and I'm sorry about that.

I totally get it, it's a built in flaw of the Lemmy/social media format. Too little supportive language cues, and too little time and/or investment to actually listen.

I appreciate you having the patience to talk this through with me.